Learning device, symmetry evaluation device, learning method, and recording medium

A symmetry evaluation device comprising:

• at least one memory configured to store instructions;
• and
• at least one processor configured to execute the instructions to:
• output a symmetry evaluation value that indicates a degree of difference between coordinates of feature points of an original image and coordinates of feature points of an inverted image, in which the original image has been axisymmetrically inverted, in a case where coordinate conversion is performed so as to cancel out a difference in coordinates between the coordinates of the feature points of the original image and the coordinates of the feature points of the inverted image due to an effect of image inversion.

A learning method executed by a computer, the method comprising:

• acquiring training data that includes an original image, and correct values of coordinates of feature points of the original image;
• generating an inverted image in which the original image is axisymmetrically inverted;
• calculating coordinates of feature points of the original image and coordinates of feature points of the inverted image;
• calculating a symmetry evaluation value that indicates a degree of difference between the coordinates of the feature points of the original image and the coordinates of the feature points of the inverted image in a case where coordinate conversion is performed so as to cancel out a difference in coordinates between the coordinates of the feature points of the original image and the coordinates of the feature points of the inverted image due to an effect of image inversion;
• and
• controlling training of a model that calculates the coordinates of the feature points such that the degree of difference indicated by the symmetry evaluation value is reduced.